CN211213114U - Arteriovenous vascular access external physical simulation device - Google Patents

Abstract

The utility model discloses an extracorporeal physical simulation device of an arteriovenous vascular access, which comprises a main body and a main body; the water outlet of the water tank is connected with the water inlet of the water tank through a pipeline; a section of stenosis model simulating a vascular stenosis model is arranged on the pipeline; a first one-way valve, a pulsating flow generating device, a second one-way valve, a first compliance chamber, a flowmeter, a first pressure gauge, a second compliance chamber and a resistance valve are sequentially arranged on the pipeline along the flowing direction of liquid; the pulsating flow generating device simulates the contraction and relaxation of the heart chamber to realize the blood suction from the vein and the blood ejection from the heart; the first and second compliance chambers are used to simulate the cushioning capacity of the arterial vessel wall; the first check valve and the second check valve are used for preventing liquid backflow; the frictional resistance of the inner wall of the pipeline and the resistance provided by the resistance valve simulate the resistance of the blood vessel. The simulator can measure hemodynamics parameters which are difficult to measure in the AVA of a hemodialysis patient.

Description

An in vitro physical simulation device for arteriovenous vascular access

technical field

The utility model belongs to the field of medical equipment, in particular to an in vitro physical simulation device for arteriovenous vascular access.

Background technique

Chronic kidney disease (CKD) is a serious disease that endangers human health. Long-term use of unnatural vascular access for dialysis treatment is bound to occur with various vascular access complications. According to relevant epidemiological surveys, venous vascular access (AVA) stenosis and occlusion are the second leading cause of hospitalization in hemodialysis patients. bit. Therefore, the detection of AVA stenosis is very important for hemodialysis patients. At the same time, with the continuous improvement of medical level, it is imperative to maintain the normal use of arteriovenous vascular access for a long time, which requires the joint efforts of medical staff and patients. Therefore, there is a need to develop a portable arteriovenous vascular access monitoring device. getting bigger. Previous people have used a variety of sensing methods to detect the state of vascular access. However, the abnormal characteristics of vascular access complications found in different studies vary. The reason for the divergence may be that previous studies were all analyzed based on clinical measured data, but the state of vascular access was affected by various other hemodynamic parameters (length, elastic coefficient, Poisson's ratio, blood density, blood viscosity, etc.). . The vascular access physical simulation model can effectively control the hemodynamic parameters of the vascular access, which provides conditions for the quantitative study of the vascular access hemodynamics.

In previous studies on simulating vascular pulsatile flow in vitro, the approximate pulsatile flow change of the vascular segment was basically achieved by changing the fluid input in the model. Due to the fixed frequency and volume of peristaltic pump, ventilator and blood pump, the pulsatile flow generated by this type of simulation model cannot accurately simulate the physiological waveform, nor can it be adjusted in a large range. Some studies have reconstructed the aortic pressure waveform by simulating the change of the left ventricular volume. This method can reproduce the aortic pressure more accurately, but the pulsatile flow waveform of the small arteries is not directly related to the ventricular volume curve. There will be large errors in vascular access.

Hemodynamics is an important part of the blood circulation system. It is mainly based on the physical laws governing blood flow. It is the same as the principle of general fluid mechanics. The research object is the relationship between blood flow, blood flow resistance and blood pressure. Blood vessels are not rigid tubes, they are elastic and distensible, so fluid dynamics based on classical viscosity cannot explain hemodynamics. The following content mainly studies the relationship between blood flow I, blood flow resistance R and blood pressure P in vascular access.

The circuit parameter model of hemodynamics is a cylinderization of the real physiological environment, and it is a bridge between solving practical problems and theories. Pathway blood pressure mechanism, providing design indications for physiological or pathological conditions. However, the introduction of the circuit parameter model to model analysis of the entire blood circulation system requires more details of the simulation, so it is beneficial to simplify some specific parts of the system. The circuit parameter model provides guidance for designing a simulation system, which can point out the relationship between variables, and then control various hemodynamic parameters by changing the parameters of the simulation system for in-depth analysis.

Utility model content

The purpose of the utility model is to provide an in vitro physical simulation device for arteriovenous vascular access, which can measure the hemodynamic parameters that are not easy to measure in AVA of hemodialysis patients, and provide a better understanding of blood flow in blood vessels. possible.

In order to realize the above-mentioned purpose of the utility model, the utility model provides the following technical solutions:

An in vitro physical simulation device for venous vascular access, comprising:

a water tank, the water tank is filled with liquid simulating blood, and the water outlet of the water tank is connected to the water inlet of the water tank through a pipeline that simulates a venous vascular access; the pipeline is provided with a stenosis model simulating a narrowed area of the blood vessel;

On the pipeline between the water outlet and the narrow model, along the liquid flow direction, a first check valve, a pulsating flow generating device, a second check valve, a first compliance chamber, a flow meter, the first pressure gauge;

On the pipeline between the narrow model and the water inlet, along the liquid flow direction, a second pressure gauge, a second compliance chamber, and a resistance valve are arranged in sequence;

The pulsatile flow generating device can simulate the contraction and relaxation of the ventricle by being capable of sucking liquid from the vein and ejecting the liquid outward, thereby realizing blood sucking from the vein and ejecting blood from the heart;

The first compliance chamber and the second compliance chamber are used to simulate the buffering capacity of the arterial vessel wall;

the first one-way valve and the second one-way valve are used to prevent the pulsatile flow generating device from generating fluid backflow when sucking blood from the vein;

The frictional resistance of the inner wall of the pipeline and the resistance provided by the resistance valve simulate the resistance of the blood vessel.

Preferably, the pulsating flow generating device comprises a chamber simulating a heart chamber, a piston is arranged in the chamber, a fixed end of the piston is connected to one end of a linear reciprocating connecting rod, a speed regulating motor is installed on the outer wall of the chamber, and the The speed regulating motor is connected to the other end of the linear reciprocating link;

The speed regulating motor drives the linear reciprocating connecting rod to perform linear motion and then drives the piston to perform linear motion in the chamber. The rotational speed of the speed regulating motor simulates the heart rate, and the movement of the linear reciprocating structure drives The stroke of the piston simulates blood flow, and the heart rate and blood flow are adjusted by controlling the speed of the motor.

Preferably, the first compliance chamber and the second compliance chamber are a sealed container in which gas and liquid coexist, the lower part of the container is liquid and the upper part is gas, and the compliance is changed by changing the pressure of the gas. Further, the first compliance chamber and the second compliance chamber are syringes. The compliance of the compliance chamber is varied by fixing the air molar content in the syringe.

Preferably, the resistance valve is a ball valve; the pipeline is a silicone tube, and the elastic coefficient and Poisson's ratio are the same as those of clinically used polymer grafts.

Preferably, the narrow model is prepared by 3D printing of a resin material, and is placed in an O-ring to form a composite body, and the composite body is closely attached to the inner wall of the pipe.

Preferably, the liquid simulating blood is a mixed solution of water and glycerol in a certain proportion, and at 28°C, its viscosity velocity is 3.2×10-6m ² /s and density is 1090kg/m ³ .

Compared with the prior art, the utility model has the following beneficial effects:

The in vitro physical simulation device for venous vascular access provided by the utility model can simulate the blood flow in the blood vessel, the simulation target is that the arterial and venous pressure pulsation and blood flow meet the real situation of AVA, and the simulated controllable parameters include heart rate, stroke volume ( blood flow), vascular resistance, arteriovenous compliance, systolic and diastolic ratio.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are just some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative efforts.

1 is a schematic structural diagram of an in vitro physical simulation device for venous vascular access provided by the present embodiment;

Figure 2 is a schematic diagram of the motion of the linear reciprocating link;

FIG. 3 is a circuit parameter diagram of an in vitro physical simulation device for venous vascular access.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present utility model more clearly understood, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and do not limit the protection scope of the present invention.

The in vitro physical simulation device for venous vascular access provided by this embodiment can simulate the pulsatile flow in the blood supply artery of a similar hemodialysis patient, so as to obtain the blood flow in the AVA under different hemodynamic parameters. The physical simulation model can adjust, measure, display and record the heart rate pulsation in the simulated AVA, and the blood pressure at the entrance and exit (simulated arterial anastomosis, venous anastomosis). As shown in FIG. 1, it includes a water tank 1, a first one-way valve 2, a pulsating flow generating device 3, a second one-way valve 4, a first compliance chamber 5, a flow meter 6, and a first pressure gauge connected in sequence through pipes. 7. Second pressure gauge 8 , second compliance chamber 9 , resistance valve 10 , stenosis model 11 .

Among them, the water tank 1 is filled with a liquid that simulates blood, and the liquid is a mixed solution of water and glycerol in a certain proportion. For example, it can be a mixed solution of 0.38:0.62. At 28 °C, its viscosity velocity is 3.2×10-6m ² The /s density is 1090 kg/m ³ .

The water outlet of the water tank 1 is connected to the water inlet of the water tank 1 through a pipeline simulating a venous vascular access; a section of stenosis model 11 simulating a vascular stenosis area is arranged on the pipeline.

On the pipeline between the water outlet and the narrow model 11, the first one-way valve 2, the pulsating flow generating device 3, the second one-way valve 4, the first compliance chamber 5, the flow meter 6, and the first pressure gauge 7 are located along the The liquid flow direction is set in sequence; on the pipeline between the narrow model 11 and the water inlet, the second pressure gauge 8 , the second compliance chamber 9 , and the resistance valve 10 are set in sequence along the liquid flow direction.

In the present invention, the pulsatile flow generating device 3 mainly simulates the contraction and relaxation of the ventricle to achieve blood suction from the vein and ejection of blood from the heart, that is, to suction the liquid from the vein and eject the liquid through the motor-driven piston. Specifically, the pulsatile flow generating device 3 includes a chamber simulating a ventricle, a piston is arranged in the chamber, a fixed end of the piston is connected to one end of a linear reciprocating connecting rod, a speed regulating motor is installed on the outer wall of the chamber, and the speed regulating motor is connected to the linear reciprocating motion the other end of the connecting rod. The speed regulating motor drives the linear reciprocating connecting rod to move in a straight line and then drives the piston to make a linear movement in the chamber. The speed of the speed regulating motor simulates the heart rate, and the stroke of the piston driven by the movement of the linear reciprocating link simulates the blood flow. By controlling the speed motor The rotational speed regulates heart rate and blood flow. The pulsatile flow waveform generated by the pulsatile flow generating device 3 is similar to that generated by the left ventricle.

As shown in Figure 2, when the speed-regulating motor pushes the piston downward through the linear reciprocating connecting rod, simulating ventricular contraction, the pulsatile flow generating device simulates cardiac ejection, and the speed-regulating motor drives the piston upward through the linear reciprocating connecting rod, simulating The ventricle dilates and the pulsatile flow generating device draws blood from the vein. The systolic and diastolic time of the ventricle is very short, so the acceleration and direction changes of the speed-regulating motor are relatively high. In addition, if the piston adopts an O-type sealing ring, it will generate a large amount of friction, and the motor power requirements are relatively high. Therefore, the utility model chooses The 220V linear AC motor with adjustable speed is used as the speed regulating motor.

The first compliance chamber 5 and the second compliance chamber 9 are mainly used to simulate the buffering capacity of the arterial vessel wall, that is, to simulate the elasticity of the blood vessel and the buffering and return of the vein, which are the inherent elastic characteristics of the vessel wall. The utility model designs the first compliance chamber 5 and the second compliance chamber 9 as a gas-liquid coexistence sealed container, the lower part of the container is liquid, the upper part is gas, and the compliance is changed by changing the pressure of the gas. According to the pressure-volume relationship of compliance, the formula is listed:

P _{fl d} =P _air +ρgh _fluid (1)

V _tank =V _fluid +V _air (2)

P _air V _air = nRT = constant (3)

Differentiation from formulas (1) to (3) can be obtained:

dP _fluid =dP _air +(ρg)dh _fluid

dV _fluid = -dV _air

Then the compliance E is:

where P _fluid and P _air are the pressures of liquid and gas, respectively, V _fluid and V _air are the volumes of liquid and gas, respectively, h _fluid is the height of the liquid, ρ is the density of the liquid, g is the acceleration of gravity, and A is the bottom area of the compliance chamber . n represents the molar amount of the gas substance, T represents the thermodynamic temperature of the ideal gas, and there is a constant: R is the ideal gas constant, and the product of the three is a constant. Since the syringe is cylindrical, V _fluid =A*h _fluid .

相对第一项很小是可以忽略，所以可通过简单的调节顺应性室中的空气体积来调节顺应性室的顺应性。because

It is negligibly small relative to the first term, so the compliance of the compliance chamber can be adjusted by simply adjusting the volume of air in the compliance chamber.

相对第一项很小是可以忽略，所以可通过简单的调节顺应性室中的空气体积来调节顺应性室的顺应性，其对应的电路参数为电容 C₀＝1/E。because

Relative to the first term, it is so small that it can be ignored, so the compliance of the compliance chamber can be adjusted by simply adjusting the air volume in the compliance chamber, and the corresponding circuit parameter is the capacitance C ₀ =1/E.

In this embodiment, the first compliance chamber 5 and the second compliance chamber 9 are selected as modified syringes. The barrel and piston of the syringe are fixed on the iron stand by the test tube clamp to ensure that the total volume of liquid and gas remains unchanged when the liquid pressure in the syringe changes.

In the venous vascular access in vitro physical simulation device, according to the fluid network theory, blood pressure and blood flow can be compared with the voltage and current in the circuit respectively, the blood flow resistance can be compared with resistance, the blood inertia can be compared with inductance, the blood flow compliance Capacitance can be used to compare, so the simulation device can be transformed into the circuit parameter model shown in Figure 3. Using this circuit model, the setting parameters of the first and second compliance chambers, resistance valves, and motors can be calculated, and the impedance, capacitive reactance, and inductive reactance of the vascular access can also be calculated through these parameters and the input and output pressure and blood flow of the vascular access. . The resistance of the blood vessel mainly comes from two parts, which are the inner wall friction resistance of the pipeline and the resistance provided by the resistance valve, wherein the inner wall friction resistance R of the pipeline can be calculated according to formula (4).

Among them, η is a constant, which can be the blood viscosity coefficient, l is the length of the blood vessel, and r is the radius of the blood vessel. The resistance valve is a manual or electric valve, which changes the resistance by changing the cross-sectional area of the valve. Since the resistance of the resistance valve is much larger than that of the connecting pipe, only the resistance of the resistance valve can be considered in the circuit parameter model. In this embodiment, a ball valve can be selected as the resistance valve.

The main source of blood flow inertia L is the difficulty of changing blood flow in the pipeline. The calculation formula is:

Among them, ρ is a constant, which can be the blood viscosity coefficient, l is the length of the blood vessel, and r is the radius of the blood vessel. Its value is small and has little effect on the current and voltage, so the blood flow inertia of the connecting pipeline is ignored in the circuit parameter diagram, and only the blood flow inertia of the vascular access is considered.

The blood flow compliance mainly comes from the elasticity of the compliance chamber and the blood vessel, wherein the capacitance of the compliance chamber is C ₀ =1/E. The capacitance C ₁ of the compliance of blood vessel elasticity can be calculated by formula (6):

Among them, l is the length of the blood vessel, r is the radius of the blood vessel, ΔD is the change in the diameter of the blood vessel, and ΔP is the change in the blood pressure. Since the compliance of the connecting pipe is much smaller than that of the first and second compliance chambers, it is ignored.

In the present invention, the first one-way valve 2 and the second one-way valve 4 are used to prevent the liquid backflow when the pulsatile flow generating device 3 sucks blood from the vein; the first pressure gauge 7 and the second pressure gauge 8 are used to measure blood vessel stenosis The simulated blood pressure before and after the model 11 , and the flow meter 6 is used to measure the simulated blood flow through the vascular stenosis model 11 .

In this embodiment, the pipeline is a silicone tube with an inner diameter of 6.0 mm, and the elastic coefficient and Poisson's ratio are the same as those of the clinically used polymer graft. It is placed in an O-ring to form a composite body, and the composite body is closely fitted to the inner wall of the pipe, and the stenosis degree of the stenosis model 11 varies from 50% to 95%.

The above-mentioned in vitro physical simulation device for arteriovenous vascular access realizes the near-physiological pulsation change of the pressure and flow of the AVA blood supply arterial pulsation flow on the basis of stable laminar flow, the pressure range: 0-26.67kPa; the pressure fluctuation amplitude: ±8kPa; the fluctuation frequency: 0-2.5Hz; flow rate: 0-2L/min.

The above-mentioned in vitro physical simulation device for arteriovenous vascular access is mainly used to measure hemodynamic parameters that are difficult to measure in AVA of hemodialysis patients, such as blood pressure, blood flow, and shear force on the vessel wall. The in vitro physical simulation device of the arteriovenous vascular access provides the possibility to further understand the blood flow in the blood vessel. At the same time, medical staff can further understand the causes of AVA complications through the in vitro physical simulation device of arteriovenous vascular access.

The in vitro physical simulation device for arteriovenous vascular access can effectively control variables in the vascular access, such as geometry, blood flow, and the like. These variables vary greatly among different patients, and are closely related to the blood flow in the blood vessels. If only the clinically measured data is used to analyze the AVA, it is difficult to accurately reflect the change of a specific variable on the AVA.

The in vitro physical simulation device of arteriovenous vascular access can provide a verification environment for different AVA complication detection methods, such as auscultation, photovolume, portable ultrasound, infrared, etc. After the corresponding transformation, the model can provide a data set with controllable variables. At the same time, the in vitro physical simulation device of arteriovenous vascular access can also be used as a verification platform for other disease detection methods, such as detecting arteriosclerosis by radial artery pulsation waveform, and verifying the prone position of AVA stenosis.

The above-mentioned specific embodiments describe in detail the technical solutions and beneficial effects of the present invention. It should be understood that the above are only the most preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, additions and equivalent replacements made within the scope of the principles of the utility model shall be included within the protection scope of the present utility model.

Claims (7)

1. an arteriovenous vascular access external physical simulation device is characterized in that, comprising: a water tank, the water tank is filled with liquid simulating blood, and the water outlet of the water tank is connected to the water inlet of the water tank through a pipeline that simulates a venous vascular access; the pipeline is provided with a stenosis model simulating a narrowed area of the blood vessel; On the pipeline between the water outlet and the narrow model, along the liquid flow direction, a first check valve, a pulsating flow generating device, a second check valve, a first compliance chamber, a flow meter, the first pressure gauge; On the pipeline between the narrow model and the water inlet, along the liquid flow direction, a second pressure gauge, a second compliance chamber, and a resistance valve are arranged in sequence; The pulsatile flow generating device can simulate the contraction and relaxation of the ventricle by being capable of sucking liquid from the vein and ejecting the liquid outward, thereby realizing blood sucking from the vein and ejecting blood from the heart; The first compliance chamber and the second compliance chamber are used to simulate the buffering capacity of the arterial vessel wall; the first one-way valve and the second one-way valve are used to prevent the pulsatile flow generating device from generating fluid backflow when sucking blood from the vein; The frictional resistance of the inner wall of the pipeline and the resistance provided by the resistance valve simulate the resistance of the blood vessel. 2 . The in vitro physical simulation device for arteriovenous vascular access according to claim 1 , wherein the pulsatile flow generating device comprises a chamber simulating a ventricle, the chamber is provided with a piston, and the fixed end of the piston is connected in a linear reciprocating manner. 3 . At one end of the moving link, a speed regulating motor is installed on the outer wall of the chamber, and the speed regulating motor is connected to the other end of the linear reciprocating link. 3. The in vitro physical simulation device for arteriovenous vascular access according to claim 1, wherein the first compliance chamber and the second compliance chamber are a sealed container in which gas and liquid coexist, the lower part of the container is liquid, and the upper part is a liquid. is a gas, the compliance is changed by changing the molar content of the gas. 4 . The in vitro physical simulation device for arteriovenous vascular access according to claim 1 , wherein the first compliance chamber and the second compliance chamber are syringes. 5 . 5 . The in vitro physical simulation device for arteriovenous vascular access according to claim 1 , wherein the resistance valve is a ball valve. 6 . 6 . The in vitro physical simulation device for arteriovenous vascular access according to claim 1 , wherein the pipeline is a silicone tube, and the elastic coefficient and Poisson’s ratio are the same as those of clinically used polymer grafts. 7 . 7 . The in vitro physical simulation device for arteriovenous vascular access according to claim 1 , wherein the stenosis model is prepared by 3D printing of resin material, and is placed in an O-ring to form a combined body, the combined body closely fit on the inner wall of the pipe.

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